After launching Google Earth, select "Directions" to bring up the start and end location input fields.

Once there, we enter our starting and ending address. In this case we're using "Austin, TX" for starting and "San Antonio, TX" for ending. Select the "Search" button when done.

In the turn-by-turn list box (below the search input fields), there should be a entry called "Route". It should already be highlighted but click it if it is not.

We need to save the route to a output file. Do this by selecting "File" off of the main menu then select "Save As". This will bring up the Save As dialog box. Enter a name and switch the output format to "KML" instead of "KMZ" then click "Save".

Now that we have the google earth route file, let's build the ARC filter file: